2 years out of Batteries

[gornoman]

Originally Posted by Wyatt2261

I Never let battey pack go below 70% of discharge.

Does this mean you use 70% of the pack's energy or 30% before you charge?

[Wyatt2261]

Gorno, I very rarely let the pack discharge 70% of its capacity, I would say I recharge the pack between 30% to 50% of battery capacity.

[sportcoupe]

D&D motors told me the current draw from the motor at max throttle cruise must drop below 70 amps otherwise batteries won't last long at all if pushed to deliver high current all the time.

They were very careful designing a motor for my speed demon cart on a recent order as several choices would have put me at 100 amps at full throttle. That would have delivered faster speeds but at the cost of my batteries and they didn't feel comfortable with that.

I ended up ordering a motor that would lower full throttle amp draw to below 70 even though I would loose some performance (speed).

[JohnnieB]

Originally Posted by Wyatt2261

Gorno, I very rarely let the pack discharge 70% of its capacity, I would say I recharge the pack between 30% to 50% of battery capacity.

I'm not sure what you mean by "70% of its capacity"
Does that mean 70% SoC (State of Charge) or 70% DoD (Depth of Discharge)? See attached chart.

Whatever scale used, the batteries shouldn't be discharged more than 50%, which is the same point on both scales.

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Batteries made by US Battery, need a bit higher on-charge voltage than other brand batteries. See attached charging recommendations.

However, your Sam's Club and Trojan batteries didn't last very long either, so the problem might be the charger and/or the way the cart is set up and the way it is used.

[scottyb]

Can you give voltage readings on charge max voltage? and pack voltage at average recharge...... also if drawing the pack to 50% discharge how long does it sit there before recharging?

I suspect a charger or charging habit problem.

[Wyatt2261]

Ok.
Here are the results:
The pack (just before shut off) showed 41.1v, the amp meter on the charger was @ 9amps

batteries 30min after charge:
6.20 / 6.20 /6.29 /6.29 /6.20 /6.20

Batteries 12hrs after charge:
6.12 / 6.12 / 6.19 / 6.19 / 6.12 / 6.12 total pack @36.8

The batteries get charged immediately after use. During Deer season usually 2 times a day. I base the amount of discharge off the state of charge meter ( led bars). Not sure how accurate it is, therefore I just ordered an analog indicator.

[patgrim00]

Get a digital meter from Scotty b it tells actual voltage in real time of your pack

[JohnnieB]

Originally Posted by Wyatt2261

Ok.
Here are the results:
The pack (just before shut off) showed 41.1v, the amp meter on the charger was @ 9amps

batteries 30min after charge:
6.20 / 6.20 /6.29 /6.29 /6.20 /6.20

Batteries 12hrs after charge:
6.12 / 6.12 / 6.19 / 6.19 / 6.12 / 6.12 total pack @36.8

The batteries get charged immediately after use. During Deer season usually 2 times a day. I base the amount of discharge off the state of charge meter ( led bars). Not sure how accurate it is, therefore I just ordered an analog indicator.

41.1V is far too low.
US Battery's recommended charge profile calls for 45.0V +/- 0.5V.

The LED bar-graph type SoC meters are notoriously inaccurate because they have a nasty habit of re-calibrating themselves to something other than 100% SoC.

The analog type are better, but the DVM type is the best.

[Wyatt2261]

So do I have an issue with my charger?

[JohnnieB]

Originally Posted by Wyatt2261

So do I have an issue with my charger?

Yes.
The on-charge voltage (41.1V) is not getting high enough. Should be 45.0V to 46.0V
The at-rest voltage (36.8V 12 hours after charger shuts off) is only 62% SoC. Fully charged is 38.2 for a 36V pack or 6.37V per 6V battery.

Your range is short and your batteries aren't lasting very long because they aren't being fully charged.

There may be excessive resistance in the charge loop causing the charge to shut off prematurely, or the charger might be malfunctioning.

This is what I use: http://www.cartsunlimited.net/48v_Battery_Charger.html